1. Field of the Invention
This invention relates to a device for connecting an end of an optical fiber and a photodetector, such as a photodiode. Such a connecting device is particularly intended to form an optoelectronic interface at a receiving end of an optical fiber in an optical fiber transmission system. The invention deals further with positioning the end of the optical fiber with respect to a photosensitive surface of the photodetector for maximum reception thereby of a light beam transmitted by the fiber.
2. Description of the Prior Art
International Patent Application No. WO 79/00099 discloses such a connecting device as comprising a U-shaped base member. A tip of a first arm of the base member carries an opto-electronic element, e.g., a a photodetector. Freely running through a hole in another arm of the base member is a bushing with a flange pressed against the base member by a spring. A sleeve solidly enveloping an optical fiber end slidably fits inside the bushing.
A micromanipulator positions an endface of the fiber end opposite an active surface of the opto-electronic element. The micromanipulator comprises a frame with a slider to which the base member is secured to move the opto-electronic device in a direction normally parallel to an axis of the fiber end. A chuck gripping sleeve is moved in two directions orthogonal to the axis of the fiber end by adjusting screws fixed to the frame.
The desired position of the fiber end with respect to the opto-electronic element is checked using conventional measurements of electrical power picked up by the photodetector from a light beam emitted through the fiber end. The desired position is fixedly maintained by bonding the sleeve inside the bushing, thereby fixing the position of the fiber end in an axial direction, and then by bonding the bushing flange to the second arm of the base member. The connecting device is then ready for use after separating the base member and the slider and after separating the sleeve and chuck.
The connecting device described in International Patent Application No. WO 79 00099 requires a special micromanipulator and other highly special members as well as many assembly and dismantling operations that result in a relatively high manufacturing cost of the device. Additionally, the positioning operation requires a biasing and amplifying circuit matched with the specific characteristics of the photodetector. Because the distance from the photosensitive surface of the photodetector to the endface of the fiber end must be on the order of a few hundredths of a millimeter, movement of the slider could result in hard contact between the fiber endface and the photosensitive surface thereby causing damage thereto.